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pubmed:abstractText |
The pathway of 3,4-dihydroxyphenylalanine undergoing metabolism via transamination and subsequent oxidative rearrangement to 2,4,5-trihydroxy-phenylacetate was investigated. 3-Methoxytyrosine does not pursue an identical course, since its corresponding keto acid is not subject to action of p-hydroxy-phenylpyruvate hydroxylase. The radiochemical synthesis of 3-methoxy-4-hydroxy[carboxy-14C] pyruvate was accomplished. This metabolite was used to demonstrate that this keto acid does not proceed through oxidative rearrangement both in vitro and in vivo. The keto acid was found to be a competitive inhibitor of the hydroxylase and can help account for some of the metabolites observed in the urine of patients treated with 3,4-dihydroxyphenylalanine.
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